AIM: Regular physical activity (PA) practice represents a key component of obesity treatment. Drawing upon Self-Determination Theory, the purpose of this study was twofold. The first aim was to evaluate among obese adolescents the impact of a supervised exercise program supporting autonomy on their motivation to practice PA at the end of the intervention. The second aim was to evaluate the impact of the program on their level of PA one month after the end of the intervention.METHODS: Eighteen obese adolescents (mean age=14.3 years, mean BMI=33.47 kg/m²) were recruited to participate in an 11-week residential obesity treatment program. They received a 45-minute supervised exercise session each week. Motivational regulations were assessed at baseline and at the end of the intervention (via the Exercise Motivation Scale). PA practice was assessed at baseline and one month after the end of the intervention (via the 7-day PA recall interview).RESULTS: The analyses revealed that adolescents’ levels of autonomy increased, that their levels of intrinsic motivation tended to increase, and that their level of external regulation tended to decrease. In addition, the participants increased their habitual PA practice one month after the end of the intervention in comparison to baseline.CONCLUSION: This study highlights that supporting autonomy during supervised exercise sessions appears as an effective strategy to promote PA among obese adolescents because it fosters internalization of the behavior.